Nothobranchius hengstleri, Valdesalici, 2007

Stefano Valdesalici, 2007, A new species of the genus Nothobranchius (Cyprinodontiformes: Nothobranchiidae) from the coastal area of northeastern Mozambique., Zootaxa 1587, pp. 61-68 : 62-66

Nothobranchius hengstleri , new species

(Figs. 1-4)

Nothobranchius species “Nassoro” MZHL-2005-14, Hengstler & Valdesalici (2006)

Holotype. ZSM 34483 (male, 41.3 mm SL); Mozambique: Cabo Delgado: about 5 km north of Nassoro village, temporary pools, not connected to any permanent river system, 10°53.222’S, 40°22.094’E, Holger Hengstler and Silverio Vendo, 18 May 2005. Collected with large hand nets and preserved after seven months of aquarium maintenance.

Paratypes. ZSM 34484 (female, 40.5 mm SL), same collection and preservation data as for holotype (upper part of caudal fin removed for DNA extraction). ZSM 34485 (female, 33.1 mm SL), 34486 (male, 30.9 mm SL), same collection data as for holotype (preserved in field).

Diagnosis. Nothobranchius hengstleri is distinguished from N. melanospilus and N. cf. melanospilus on the basis of both meristic and morphometric data, male and female coloration, and by a more convex dorsal profile. Male N. hengstleri differs from male N. melanospilus in having a greater body depth (30.4-31.8 vs. 29.3-30.3 % SL), a longer head (33.3-33.4 vs. 26.8-28.3 % SL), a longer prepelvic length (49.6-50.1 vs. 45.6-48.9 % SL); males and females have fewer scales in longitudinal series (25-26 vs. 31-32).

Male N. hengstleri differs from male N. cf. melanospilus in having a greater body depth (30.5-31.8 vs. 25.6-28.2 % SL), a longer head (33.3-33.5 vs. 29.5-32.6 % SL); males and females have fewer scales in the longitudinal series (25-26 vs. 29-30).

Males differ from males of the other two species in having a deeper red coloration over the entire body and head, a spotted anal fin (well defined brown spots over entire fin vs. few spots limited at base), a different caudal-fin pattern (deep red, with a well defined complete black margin vs. red, without any particular marking or with thin rudimentary black margin sometimes reduced on upper and lower angle), and a different caudal fin shape (perfectly rounded vs. rounded to subtruncate). Female N. hengstleri differ from female N. melanospilus by the spots on body and fins (absent vs. present) and by the caudal fin shape indicated immediately before. They also differ from female N. cf. melanospilus by the spots on body and fins (absent vs. present but rudimentary in analyzed populations; absent in other populations) (Seegers, 1986; 1997; 2003; Rosenstock, 2003).

Among other closely related species, male N. hengstleri differs from male N. vosseleri in having a longer head (33.3-33.4 vs. 25.1-31.5 %SL), anal fin pattern (spots forming approximately three or four arch-like stripes in middle part of fin vs. small spots extending on fin rays and irregular stripes), male N. vosseleri from “Korogwe” area by dorsal and anal fins coloration (yellow-green vs. yellow-grey to pale blue), males and females with fewer scales in longitudinal series (25-26 vs. 25-31), and fewer anal fin rays (14-16 vs.15-18). Male N. hengstleri differs form male N. interruptus in having a deeper red colorations over the entire body and head, caudal fin coloration (deep red with complete black margin vs. pale to clear red with irregular blue-grey to almost colorless border), dorsal fin coloration (yellow-green, with red to brown spots vs. bluegrey to olive with dark grey spots), anal fin coloration (yellow-green with red/brown spots vs. olive-yellow to pale blue with some grey spots near fin base), males and females with fewer scales in longitudinal series (25- 26 vs. 27-32), and caudal fin shape (perfectly rounded vs. subtruncate).

Male N. hengstleri differs from male N. jubbi in having a deeper red colorations over the entire body and head, dorsal fin coloration (yellowish with red/brown spots vs. blue-grey to olive with red brown spots), anal fin coloration (yellow-green, with red-brown spots vs. olive-yellow to pale blue with some grey spots near fin base), caudal fin coloration (deep red with complete black margin vs. blue-grey with a pattern of red- brown spots and a white margin in blue morph and clear red followed by a wide blue-grey band and white border in red morph), female N. hengstleri differs from female N. jubbi in body and unpaired fins pattern (not marked vs.dark border on body scales and small dark gray marking at base of fins), males and females with fewer scales in longitudinal series (25-26 vs. 29-32), fewer dorsal (13-16 vs.15-20) and anal fin rays (14-16 vs.15- 19), caudal fin shape (perfectly rounded vs. subtruncate).

Male N. hengstleri differs from male N. elongatus in having a deeper red colorations over the entire body and head, anal fin coloration (yellow-green, with red/brown spots vs. yellow-grey with few red spots near fin base); males and females have fewer scales in longitudinal series (25-26 vs.30-32), fewer anal fin rays (14- 16 vs.16-18), and caudal fin shape (perfectly rounded vs. subtruncate).

Description. Morphometric data appear in Table 1.

A robust, moderately deep-bodied Nothobranchius with pointed snout, terminal mouth directed upward. Dorsal fin rays 13-16; anal fin rays 14-16. Longitudinal series of scales 25-26 + 2-4 on caudal fin base. Cephalic squamation pattern variable, with one specimen (ZSM 34486) showing G-type. Anterior neuromast series on head ‘open’ type; central series in two shallow grooves, lined with low lobes; posterior cephalic neuromast series with curved shallow pits on each side. Preopercular neuromast system in open groove, distal ridge slightly overlapping opercle. One neuromast on each scale of mid-lateral line.

Males. Body profile convex on dorsal and ventral margins, slightly concave on caudal peduncle posterior to dorsal and anal fins. Greatest body depth observed at level of pelvic fins base. Dorsal and anal fins rounded, their tips with rudimentary filamentous rays. Caudal fin perfectly rounded. Membranes of pelvic fins fusing near the base, tips reaching urogenital papilla. Dorsal and anal fins with small papillate contact organs. Opercular membrane projecting from opercle, distal edge slightly wrinkled.

Females. Body less compressed and deep compared to males. Dorsal fin rounded; anal fin triangular, with rounded tip; caudal fin perfecly rounded. Anal fin positioned more posteriorly compared to males. Membranes of pelvic fins fusing near the base, tips reaching urogenital papilla. Opercular membrane not projecting from opercle.

Maximum observed size of males 41.3 mm SL. Maximum observed size of females 40.5 mm SL.

Color in life. Male (Fig. 3). Scales on body and head light blue, with distinct red margins, resulting in a reticulated pattern. Scale margins in ventral area orange. Snout, throat, frontal and upper/dorsal part of head deep red. Scales on middle part of caudal peduncle and on caudal fin base red. Dorsal fin yellowish-green, with pattern of red/brown spots forming arch-like stripes and narrow lines; spots on distal part of fin smaller and more dense, with white to light blue border and with thin submarginal blue band. Anal fin yellow-green, with pattern of red/brown spots forming approximately three or four arch-like stripes in middle part of fin; spots near base distally fused in narrow lines extending onto fin rays; fin with white to light blue border. Caudal fin deep red, with complete black margin. Pelvic fins light yellow-green, with some brown spots parallel to fin rays, light blue border and brown submarginal band. Pectoral fins hyaline, with light blue margin. Iris golden, with light blue iridescences and faint dark vertical bar.

Female (Fig. 4). Body pale olive-brown, darker grey-brown dorsally; light brown to almost silvery-white ventrally. Flank scales with light blue iridescence. Unpaired and paired fins hyaline. Iris golden, with a faint dark vertical bar.

Color in alcohol. Male (Fig.1). Body scales light brown to whitish, almost all scales with distinct dark red margin. Dorsal fin light brown with a pattern dark brown spots. Anal fin light brown. Caudal fin light brown with dark red lines exending on fin rays. Pelvic and pectoral fins light brown. Iris bluish.

Female (Fig. 2). Body light brown to whitish, scales with a narrow brown margin. Opercular and ventral area yellowish to light orange. Unpaired and paired fins pale light brown to whitish. Iris blueish.

Distribution and habitat. (Figs. 5-6). N. hengstleri is only known from the type locality, a temporary pool in a small coastal plateau, about 10 km long by 20 km wide, altitude 67 m, in northeastern Mozambique, approximately 5 km north Nassoro village, Cabo Delgado province. The species probably has a wider range, but this can only be ascertained through additional collecting.

The very small pool was at the time of collection about 6 m long, 1.5 m wide and shallow (about 0.10 m deep). No aquatic vegetation was present, with only dry grass along the shore. The water was brown and turbid and the pH 7.5. No other fish species were present.

Etymology. The new species is named in honor of the collector, Mr. Holger Hengstler of Munich, Germany.

Discussion

Additional and modified synapomorphies important in defining the N. melanospilus species group are: maximum observed body size (over 30 mm SL), a relatively elongate to moderately deep body (less than 35% of SL), variable cephalic squamation, pointed triangular head, dorsal profile gently convex from snout to end of dorsal-fin base, male coloration consisting of uniform red reticulation over blue scales and a dorsal fin with white to light blue rudimentary filamentous rays. The last character was not mentioned in the redescription of N. vosseleri (Wildekamp et al, 1998), but is present in some specimens; see illustration in Seegers (1997: 82).

Nothobranchius hengstleri is a member of this group, presenting all of the diagnostic features of this complex. Aspects of the colour pattern and morphology suggest that N. hengstleri is more closely related to N. vosseleri than to the others members of the group.

The distribution of the species group is almost entirely restricted to the area from southern Somalia to Mozambique (north of the Zambezi River), a pattern congruent to the paleo-ichthyofaunal boundaries proposed by Stewart (2001).